Automatic valve

ABSTRACT

An automatic valve in which a valve body is located in a central chamber of a housing and fluid flow is directed through passages of progressively decreasing flow area formed between the valve body and the inside wall of the housing, thereby causing throttling of the flow in the chamber. A spring acting on the valve body balances the resulting pressure differential between the upstream and downstream sides of the valve body to hold the valve body in an open position during normal fluid flow. Should the flow exceed a predetermined amount, the pressure differential exceeds the force of the spring and the valve body moves to a closed position, shutting off flow through the system. To prevent an abrupt shutoff of the fluid flow, a damping device is provided for limiting the closing speed of the valve body.

United States Patent 1191 Katzer et al.

1451 May 29, 1973 1 AUTOMATIC VALVE 3,472,275 l0/l969 Castro et a1...137/49s x [75] Inventors: Johannes Kan; Franz Lopic both 3,605,8029/l97l Hertell ..l37/514.5

. f N l G 0 cu U m ermany Primary Examiner-Alan Cohan [7 AsslgneelKllPeX Geafus, Switzerland Assistant Examiner-David J Zobkiw [22] l Jam24, 1972 A ttorney-Granville M. Brumbaugh, Eben M.

Granes, Mark N. Donohue et a1. [211 Appl. No.: 220,220

[57] ABSTRACT [30] Foreign Application prkl'ity Data An automatic valvein which a valve body is located in Jan. 28, 1971 Gennany ..P 21 03948.5 a Central chamber a musing and fluid is directed through passagesof progressively decreasing 52] us. c1. ..137/s14.s, l37/5l6.29,137/517, flow area formed between the valve y and the l37/536, 137/540,251 IDIG. 1 side wall of the housing, thereby causing throttling of [51]Int. Cl ..Fl6k 17/04 the flow in the chamber. A spring acting on thevalve [58] Field of Search ..137/460, 514, 514.3, body balances theresulting pressure differential l37/5l4.5,5l4.7,5l6.25, 516.27, 516.29,between the upstream and downstream sides of the 517, 498, 536; 25l/DIG. l valve body to hold the valve body in an open position I duringnormal fluid flow. Should the flow exceed a [56] References Citedpredetermined amount, the pressure differential exi ceeds the force ofthe spring and the valve body UNITED STATES PATENTS moves to a closedposition, shutting off flow through 955,043 4/1910 Barr et a1 137/5141the system. To prevent an abrupt shutoff of the fluid 0 ,880 5/1950Pelton 37/5l4- X flow, a' damping device is provided for limiting the2,968,315 1/l 961 Fisher ..l37/5l7 closing speed of the valve body2,142,473 7 7/l964 19 Claims, 5 Drawing Figures PAIENIE was I975 SHEET 20F 2 Fig.5

l AUTOMATIC VALVE BACKGROUND OF THE INVENTION This invention relates toan automatic shut-off valve and, more particularly, to a valve of thistype which is responsive to the flow of fluid through the valve housingto allow normal flow there through but which closes to terminate flowwhen the flow through the housing exceeds a predetermined amount.

A great number of water consuming devices, e.g., domestic machines suchas dishwashers, washing machines and the like, are coupled to anexternal water supply system or other equipment by means of flexiblehoses equipped with suitable connections. Typically, flow through thehoses and connections is restricted by a solenoid valve, nozzle or otherflow regulating device located in the machine to less than the maximumpossible throughput. Hence, if a hose connection comes loose or breaksduring operation, large quantities of water can flow out in a very shorttime, possibly causing extensive damage. As these machines are highlyautomatic, they are seldom attended during operation. The likelihood oflarge volumes of water escaping in the event of a connection or hosefailure is therefore compounded.

SUMMARY OF THE INVENTION valve without adversely affecting the rest ofthe fluid system.

These and other objects are attained, in accordance with the invention,by the provision of a valve including a housing having a chamber with afluid inlet and a fluid outlet, a valve body positioned within thechamber and movable between an upstream open position and a downstreamclosed position and a spring also located in the chamber for urging thevalve body in the upstream direction. Fluid flow is between the valvebody and the chamber wall and results in the development of a pressuredifferential across the upstream and downstream sides of the valve body.During normal volume flow, the spring force balances the pressuredifference and holds the valve body in an open position. When the flowvolume exceeds a predetermined amount, however, the pressure differenceincreases until it overcomes the spring force and the valve body movesto the closed position, at which all flow through the valve is shutoff.

If the fluid flow were shutoff too abruptly, the resulting water shock,or water hammer", could damage the system. To prevent this a dampingdevice is provided for slowing the movement of the valve body betweenthe normal open position and theclosed position. The damping deviceincludes a cup-shaped cylinder disposed in a downstream portion of thechamber, where it receives in longitudinally slidably relation anextension of the valve body. Fluid trapped within the cylinder ispermitted to escape in a controlled manner upon downstream travel of theextension, i.e., upon movement of the valve body from the open to theclosed position. This damping action allows the valve to close slowly,so that, for example, a few seconds pass until complete shutoff of theflow is effected. Damage due to water shock" is thus avoided. Althoughit takes a few seconds for the valve to close in case of excessive flowthrough the housing, this time is insignificant in view of what mighthappen if there were no automatic valve for preventing the uncontrolledoutflow of water in case of hose or connection damage. Moreover, thedamping feature prevents the valve from closing inadvertently if, at thebeginning of operation, the amount of fluid consumed by the connectedequipment is larger than normal. As long as a certain position of thevalve body is not exceeded, the valve opens again automatically afterthe flow volume returns to normal.

According to another feature of the invention, the valve body cooperateswith a non-return or checkvalve seat located upstream of the normal openposition of the valve body when there is no flow between the inlet andthe outlet, thereby preventing reverse flow through the valve. This isparticularly desirable feature, for example, with washing machines.

As a further feature of the invention, the flow passage lying oppositethe normal open position of the valve body preferably is formed suchthat as the valve member 25 moves downstream the cross-sectional flowarea between the valve body and the chamber wall progressively decreasesin size. Then if the flow volume exceeds the predetermined maximumdesired, i.e., the maximum which the valve is designed to permit, theclosing force acting on the valve body will increase progressively asthe valve body moves downstream due to the throttling effect of thedecreasing flow area, until complete shutoff is reached.

BRIEF DESCRIPTION OF THE DRAWINGS An understanding of the invention maybe gained from a consideration of the following detailed description ofrepresentative embodiments thereof, taken in conjunction with theaccompanying figures of the drawings, wherein:

FIG. 1 is a longitudinal sectional view of a valve constructed inaccordance with the invention in which the valve body is in thenon-return position, i.e., seated against the non-return valve seat;

FIG. 2 is another longitudinal sectional view, showing the valve body inthe position assumed during normal volume flow;

FIG. 3 is a sectional view similar to FIGS. 1 and 2, but with the valvebody in the closed position;

FIG. 4 shows a second embodiment of the damping device of the invention;and

FIG. 5 shows a third embodiment of the damping device.

DESCRIPTION OF A PREFERRED EMBODIMENT In the embodiment illustrated inFIGS. 1 to 3, the automatic valve has a housing 11 of injection-moldedplastic having a fluid inlet 12, a fluid outlet 13 and a chamber leadingtherebetween. The fluid inlet 12 has an internal thread 14 which may bescrewed, for example, on to a tap. A washer 15 provides a seal betweenthe tap and the housing 11. The fluid outlet 13 is formed with anexternal thread 14' corresponding to the internal thread 14, and isadapted to receive a nipple 17 to provide a quick-acting plug connectionbetween the automatic valve and an external hose (not shown). Interposedbetween the nipple and the main housing 11 is a sealing washer l6.

Inserted in the housing 11, in the region of the inlet 12, is a ringmember whose inner surface 18 converges in the upstream direction toform a non-return or check-valve seat, as is more fully describedhereinafter. The ring member is held in place by the washer 1S.

Downstream of the valve seat 18, the housing chamber has a generallyconical portion 19, followed by a generally cylindrical portion 20. Thewalls of the portions 19 and 20 are interrupted by circumferentiallyspaced recesses 21' in the form of slots.

A cup-shaped cylinder 22, open at the upstream end, is positioned in thechamber portion lying downstream (see arrow 21 for direction of flow) ofthe cylindrical portion 20. The cylinder 22 has a smaller outer diameterthan the inner diameter of the cylindrical portion 20, thereby affordinga clearance between the facing walls ofthe cylinder 22 and thesurrounding chamber for the formation of flow passages 23 which connectthe cylindrical chamber portion 20 to the fluid outlet 13.

A valve body 25 is slidably mounted in the housing chamber. The valvebody 25 is substantially symmetrical with respect to its axis and has asection 26 of enlarged diameter that is conically shaped at each sideand which is grooved peripherally at its region of maximum diameter tocarry a seal ring 27, conveniently an O-ring of suitable construction.The section 26 is followed by a substantially cylindrical piston-shapedextension 28 of reduced diameter whose downstream section 29 extendsinto and is guided by the inner wall of the cylinder 22. The guidesection 29 is constituted by crosswise arranged ribs between which ports30 are formed (see also FIGS. 4 and 5). An O-ring 31 is positioned in acircumferential slot between the upstream portion of extension 28 andguide section 29.

In the embodiment shown in FIGS. 1 to 3, there extends over aconsiderable part of the length of the inner wall of cylinder 22, arecess 32 leading to the open end of the cylinder. The recess 32functions as an escape port for fluid located in the cylinder 22. Acompression spring 33 is positioned in the cylinder 22 and is supportedby the bottom of the cylinder and by the guide section 29 of the valvebody. The spring always tends to urge the valve body 25 against thedirection of flow.

FIG. 1 illustrates the position of the valve body 25 in the absence offlow through the valve from inlet 12 to outlet 13. Under theseconditions, the spring 33 urges the valve body 25 in a direction againstthe direction of flow (arrow 21) so that the O-ring 27 rests against thenon-return valve seat 18 and prevents any flow of fluid against thenormal direction of flow 21, i.e., in the upstream direction. The guidesection 29 guides the valve body 25 in its movement toward and away fromthe valve seat 18.

When fluid, e.g., water, from a tap or other connection, is permitted toflow in the direction 21, the pressure of the fluid acts upon the upperend of the valve body 25 and forces the valve body downward against theresistance of the spring 33 to an open position, such as thatillustrated in FIG. 2. Thereupon, the water flows through the inlet 12,the recesses 21 between the valve body 25 and the housing 11 and theports 23 to the fluid outlet 13. The preferred open position of thevalve body 25 is such that the O-ring 27 is located in the cylindricalchamber portion 20. So positioned, the O-ring 27, and the valve bodyitself, is guided by the wall portions lying between the recesses 21.Consequently, knocking or vibrating of the valve body is prevented whenat the normal open position.

flow-throttling or restricting cross section is formed' whose respectivesize is determined by the depth of the recesses 21 at the point wherethe O-ring 27 is located. Desirably, the recesses 21 are shaped so thatthe crosssectional flow area progressively decreases in the downstreamdirection. In other words, the further downstream the valve body 25moves, the smaller the flow area becomes. This is accomplished accordingto the invention by tapering the recesses 21' inwardly in the downstreamdirection. (See FIGS. 1 to 3).

Throttling of the fluid flow in this manner causes a pressuredifferential to be developed between the upstream and downstream sidesof the valve body portion 26. The spring 33 is chosen so that, in thenormal open position of the valve body 25 depicted in FIG. 2, the forceof the spring balances this pressure differential, holding the valvebody in a stationary state. Since the O-ring 27 is supported by thechamber wall, it remains in the proper position on the valve body 25.

Now, should a failure occur in the water consumer equipment connected tothe valve or in the hose leading thereto which, for example, may resultwhen a connection comes loose accidentally, the flow rate through, thevalve will increase considerably. Because of the increased flow, agreater throttling effect will take place in the annular clearancebetween the chamber portion 19 and the O-ring 27 and between therecesses 21 and the O-ring 27 with the result that the pressuredifferential across the valve body portion 26 will increase. Therefore,the spring will be further compressed and the valve body 25 shiftedstill further in the direction of flow. Because the recesses 21 aretapered in the direction of flow, the throttling is progressive. If theincreased flow continues for some time, say a few seconds for example,the valve body will be urged far enough in the direction of flow for theO-ring 27 to reach section 20 of the cylindrical portion 20 of thechamber which section is not interrupted by recesses and which acts as avalve seat for the O-ring. Flow through the valve is thus completelyshutoff. This position of the valve body is shown in FIG. 3.

It should be noted that the valve seat formed by section 20' isself-cleaning as a result of the movement of the sealing ring 27 alongsection 20' during operation of the valve. Hence, any disruption of sealintergrity due to the build-up of foreign matter on the chamber wall atsection 20 is avoided.

If the flow through the system suddenly increases, which is probablewhen the connecting hoses are damaged, the valve body 25 could reach theclosed position depicted in FIG. 3 very rapidly, shutting off flowthrough the valve abruptly. The kinetic energy of the fluid column infront of the valve would then be released in fractions of a second,which could result in a heavy pressure rise in the piping possiblycausing damage. To prevent this, provision is made to dampen, or slow,the closing speed of the valve body 25. Upon downstream movement of thevalve body 25 from the open position shown in FIG. 2 to the closedposition of FIG. 3, the O-ring 31 penetrates into the cylinder 22 andrests against the inside wall of the cylinder, thereby substantiallysealing-off its open end. Hence, fluid trapped within the cylinder canescape only through the recess.32. As mentioned, the recess 32 allows acontrolled outflow of fluid from the cylinder to the cylindrical chamberportion 20, and in this way prevents any sudden closure of the valve. Atypical closing time might, for example, range between 3 to seconds.

Again, the foregoing clamping structure also prevents any short-timeincrease of flow, which might occur when the water consuming equipmentis initially filled to operating condition, from resulting in a closureof the valve. This result can be achieved by suitably designing thevalve body 25, the chamber portions 19 and 20 and the recesses 21 aswell, such that if the increased flow diminishes shortly before thevalve body is in its final closed position, the force of the spring 33again prevails and returns the valve body 25 to the open positionillustrated in FIG. 2.

Since the ports in the guide section 29 allow fluid flow out of thecylinder 22 during movement of the valve body 25 from the position shownin FIG. 1 to the normal open position portrayed in FIG. 2, excessivedamping of the movement of the valve body 25 in the normal openoperating range is prevented. Under certain circumstances, however, acertain amount of damping may be desirable in order to prevent knockingof the valve body.

FIG. 4 shows a second embodiment of the damping structure of theinvention. In this embodiment, the cylinder 22', corresponding tocylinder 22 in FIGS. 1 to 3, has no wall recess 32. The seal 31 in theform of an O-ring lies in a groove 40, whose width and depth are eachgreater than the diameter of the O-ring (viewed in cross section). Thedepth is so large that, where the seal 31 engages the cylinder 22', theinner diameter of the O-ring does not bear against the inner wall of thegroove, i.e., the dimension of the inner wall of the groove is less thanthe inner dimension of the O-ring.

Thus, the fluid in cylinder 22', which in FIG. 4 presses from belowagainst the O-ring, can penetrate into the groove 40. On downstreammovement of the valve body 25, the O-ring 21 is urged by the force ofthe fluid flowing beneath it into sealing engagement with the upstreamsides of the groove 40. Formed in the upstream side 41 are one or morerecesses 42 which connect the interior of the groove with the spacebetween the valve body 25' and the cylinder 22 upstream of the O-ring31'. The recess or recesses 42 provide an escape passage or passagesthrough which the fluid can flow out of the cylinder in a controlledmanner. Movement of the valve body 25' is therefore damped as it movestoward the closed position. The capability of the O-ring 31 to float"within the groove 40 and the flow of fluid through the groove have theadvantage of purging the O-ring 31 of foreign matter which otherwisemight be deposited thereon and interfere with its operation. In the samemanner, the flow through the groove 40 and the-recess or recesses 42keeps them free from impurities. This feature is particularly importantbecause in the usual situation the valve will be required to close veryrarely, i.e., only in an emergency, but then effectively so as toprevent any damage.

FIG. 5 shows yet another embodiment of a damping device. The cylinder22', the sealing ring 31, and the dimensions of the groove 40' areessentially the same as in FIG. 4. Instead of a recess or recesses 42,however, one or more projections 43 are provided on the upstream side 41of the groove 40. Here, too, the lifting of the sealing ring from theside 41 produces a fluid escape passage which constantly isself-cleaning.

Furthermore, an escape passage may be provided to advantage by forming adownwardly and inwardly inclined rib, preferably of an irregulartriangular shape, extending axially along and perpendicularly from theinner wall of the cylinder 22'. The lower surface of the rib wouldextend essentially radially from the cylinder wall, and as the valvebody moved downward, the rib would force a portion of the O-ring 31',which may also be floating, away from the cylinder wall thereby forminga leakage path for the fluid. The O-ring 31" would not be damaged as itwould ride down the inclined surface which is essentially parallel tothe axis of the cylinder.

The above hydraulic damping devices have been found to be soadvantageous that, in the embodiments of FIGS. 4 and 5, for example, anyinfluence of friction was largely eliminated. In this regard, it shouldbe noted that the influence of friction must also be considered fordamping and may be used therefor.

It will be appreciated from the foregoing that the automatic shutoffvalve of the invention affords many advantages, including a relativelysimple, low cost construction. With the exception of the spring 33, forinstance, it can be fabricated of parts which are made chiefly ofinjection-molded plastic. In this connection, it is very advantageousif, instead of being separate as in the embodiment shown in FIGS. 1through 3, the nipple 17 is integrally molded to the housing, therebysimplifying the flow conditions. Moreover, the provision for straightflow through the valve without any major alterations in the flowdirection limits the pressure drop and also contributes to thesimplified construction of the valve.

Assembly and disassembly for cleaning or any performance testing whichmay be necessary are also very simple. Thus, the cylinder 22, the spring33 and the valve body 25 may be simply inserted into the housing fromthe fluid'inlet l2 and thereafter held in place by insertion of the ringmember carrying valve seat 18.

It will be understood by those skilled in the art that theabove-described embodiments are intended to be merely exemplary, in thatthey are susceptible of modification and variation without departingfrom the inventive concepts disclosed. For example, instead of employingwall recesses 32, the flow passages required for damping may also beachieved by providing bores in the valve body or in the cylinder.

Although the additional function of the valve as a non-return or check,valve is very advantageous, the

valve seat 18 may be omitted or suitably pierced if the non-returnfunction is not desired, so that the water can direction the mode ofoperation of the valve may be varied within wide limits. Aside from thesize of the cross sections, which determines the point of change, i.e.,the position of flow volume at which the transition to the closedposition takes place, the point of change may also be varied withinlimits by a nonlinear design of the taper of the restricting crosssections or by steps in these cross sections. It is to be noted furtherthat the point of change" is also influenced by the strength of thespring, so that an adjustment of the desired flow volume may be effectedwithin certain limits by utilizing springs of different strengths. Onthe other hand, by the aforementioned cross-sectional changes, e.g., bya first higher and then lower degree of taper of the cross section, theeffect of the spring strength and the closing speed can be diminished.All such variations and modifications, therefore, are intended to beincluded within the spirit and scope of the invention as defined in theappended claims.

We claim:

1. An automatic shut-off valve comprising:

a housing having a chamber with a fluid inlet and a fluid outlet;

a valve body located within the chamber and being movable between anupstream open position and a downstream closed position, the valve bodyhaving an upstream portion of enlarged diameter and a downstreamextension of smaller diameter;

means defining a cup-shaped cylinder in a downstream portion of thechamber, the cylinder being open to the chamber at the upstream end andthe smaller diameter extension of the valve body being slidably receivedtherein;

means defining at least one, first flow passage between the valve bodyand the chamber opposite the upstream open position in flowcommunication with the fluid inlet;

means defining at least one, second flow passage between the cylinderand the chamber in flow communication with the fluid outlet and, whenthe valve body is at the open position, with the first flow passage;

seal means carried in part by the enlarged diameter portion of the valvebody for shutting off fluid flow between the first and second flowpassages when the valve body is at the closed position;

spring means for urging the valve body against the direction of flow soas to maintain the valve body at the open position under normal flowthrough the valve but to permit the valve body to move to the closedposition when the flow exceeds a predetermined maximum quantity; and

means for permitting controlled fluid escape from the cylinder upondownstream movement therein of the smaller diameter extension of thevalve body, thereby to afford a damping action on the movement of thevalve body from the open to the closed position.

2. An automatic valve according to claim 1, further comprising valveseat means within the chamber upstream of the open position for coactingwith the enlarged portion of the valve body to prevent fluid flowthrough the valve in the upstream direction, the valve body beingmovable into sealing engagement with the valve seat means by the springmeans in the absence of fluid flow in the downstream direction.

3. An automatic valve according to claim 1, further comprising valveseat means within the chamber upstream of the open position for coactingwith the seal means carried by the enlarged diameter portion of thevalve body to prevent fluid flow through the valve in the upstreamdirection, the valve body being movable into sealing engagement with thevalve seat means by the spring means in the absence of fluid flow in thedownstream direction.

4. An automatic valve according to claim 1, wherein the means definingthe first flow passage comprises at least one recess in the chamberwall.

5. An automatic valve according to claim 1, wherein the first flowpassage has a progressively decreasing cross-sectional flow area betweenthe valve body and the chamber wall in the direction of flow.

6. An automatic valve according to claim 5, wherein the means definingthe first flow passage comprises a plurality of recesses in the chamberwall.

7. An automatic valve according to claim 6, wherein the means definingthe first flow passage further comprises chamber-wall portions lyingbetween the recesses, the chamber-wall portions guiding the valve bodyduring at least a portion of the movement thereof from the open to theclosed position.

8. An automatic valve according to claim 1, wherein the seal meansincludes a peripheral seal member carried by the enlarged diameterportion of the valve body and dimensioned to coact with the chamber wallto shut off fluid flow when the valve body is at the closed position.

9. An automatic valve according to claim 8, wherein the valve body has agenerally circular cross-section, the peripheral seal member comprisesan O-ring and the portion of the chamber wall with which the seal membercoacts is generally cylindrical.

10. An automatic valve according to claim 8, further comprising valveseat means within the chamber upstream of the open position for coactingwith the peripheral seal member on the valve body to prevent fluid flowthrough the valve in the upstream direction, the peripheral seal memberbeing movable into engagement with the valve seat means by the springmeans in the absence of fluid flow in the downstream direction.

11. An automatic valve according to claim 10, wherein at least portionsof the peripheral seal member contact the chamber wall as the valve bodymoves between the open position and the closed position so as to guidethe movement of the valve body.

12. An automatic valve according to claim 1, wherein the means forpermitting controlled fluid escape from the cylinder comprises at leastone recess in the cylinder wall.

13. An automatic valve according to claim 1 further comprising:

an annular groove formed on the outer periphery of the smaller diameterextension of the valve body;

a seal ring positioned in the annular groove for cooperating with thewall of the cylinder upon movement of the valve body to the closedposition, the outer dimension of the inner wall of the annular groovebeing smaller than the inner dimension of the seal ring and thedimension of the groove in the direction of flow being larger than thecorresponding dimension of the seal ring, whereby the seal ring does notrest against the inner wall of the groove nor the downstream side of thegroove when the seal ring is moved downstream within the cylinder.

14. An automatic valve according to claim 13, wherein the means forpermitting controlled fluid escape from the cylinder includes meansassociated with the upstream side of the annular groove for permittingfluid flow past the inner side and upstream side of the seal ring to theregion of the cylinder upstream of the seal ring.

15. An automatic valve according to claim 14, wherein the meansassociated with the upstream side of the groove comprises a recessformed in the upstream groove side in flow communication with the regionof the groove behind the seal ring and the region of the cylinderupstream of the seal ring.

16. An automatic valve according to claim 14, wherein the meansassociated with the groove means comprises a projection extendingdownstream from the upstream groove side so as to prevent at least aportion of the seal ring from making sealing engagement with theupstream side.

17. An automatic valve according to claim 1, wherein the space betweenthe cylinder and the chamber wall. l=

1. An automatic shut-off valve comprising: a housing having a chamberwith a fluid inlet and a fluid outlet; a valve body located within thechamber and being movable between an upstream open position and adownstream closed position, the valve body having an upstream portion ofenlarged diameter and a downstream extension of smaller diameter; meansdefining a cup-shaped cylinder in a downstream portion of the chamber,the cylinder being open to the chamber at the upstream end and thesmaller diameter extension of the valve body being slidably receivedtherein; means defining at least one, first flow passage between thevalve body and the chamber opposite the upstream open position in flowcommunication with the fluid inlet; means defining at least one, secondflow passage between the cylindeR and the chamber in flow communicationwith the fluid outlet and, when the valve body is at the open position,with the first flow passage; seal means carried in part by the enlargeddiameter portion of the valve body for shutting off fluid flow betweenthe first and second flow passages when the valve body is at the closedposition; spring means for urging the valve body against the directionof flow so as to maintain the valve body at the open position undernormal flow through the valve but to permit the valve body to move tothe closed position when the flow exceeds a predetermined maximumquantity; and means for permitting controlled fluid escape from thecylinder upon downstream movement therein of the smaller diameterextension of the valve body, thereby to afford a damping action on themovement of the valve body from the open to the closed position.
 2. Anautomatic valve according to claim 1, further comprising valve seatmeans within the chamber upstream of the open position for coacting withthe enlarged portion of the valve body to prevent fluid flow through thevalve in the upstream direction, the valve body being movable intosealing engagement with the valve seat means by the spring means in theabsence of fluid flow in the downstream direction.
 3. An automatic valveaccording to claim 1, further comprising valve seat means within thechamber upstream of the open position for coacting with the seal meanscarried by the enlarged diameter portion of the valve body to preventfluid flow through the valve in the upstream direction, the valve bodybeing movable into sealing engagement with the valve seat means by thespring means in the absence of fluid flow in the downstream direction.4. An automatic valve according to claim 1, wherein the means definingthe first flow passage comprises at least one recess in the chamberwall.
 5. An automatic valve according to claim 1, wherein the first flowpassage has a progressively decreasing cross-sectional flow area betweenthe valve body and the chamber wall in the direction of flow.
 6. Anautomatic valve according to claim 5, wherein the means defining thefirst flow passage comprises a plurality of recesses in the chamberwall.
 7. An automatic valve according to claim 6, wherein the meansdefining the first flow passage further comprises chamber-wall portionslying between the recesses, the chamber-wall portions guiding the valvebody during at least a portion of the movement thereof from the open tothe closed position.
 8. An automatic valve according to claim 1, whereinthe seal means includes a peripheral seal member carried by the enlargeddiameter portion of the valve body and dimensioned to coact with thechamber wall to shut off fluid flow when the valve body is at the closedposition.
 9. An automatic valve according to claim 8, wherein the valvebody has a generally circular cross-section, the peripheral seal membercomprises an O-ring and the portion of the chamber wall with which theseal member coacts is generally cylindrical.
 10. An automatic valveaccording to claim 8, further comprising valve seat means within thechamber upstream of the open position for coacting with the peripheralseal member on the valve body to prevent fluid flow through the valve inthe upstream direction, the peripheral seal member being movable intoengagement with the valve seat means by the spring means in the absenceof fluid flow in the downstream direction.
 11. An automatic valveaccording to claim 10, wherein at least portions of the peripheral sealmember contact the chamber wall as the valve body moves between the openposition and the closed position so as to guide the movement of thevalve body.
 12. An automatic valve according to claim 1, wherein themeans for permitting controlled fluid escape from the cylinder comprisesat least one recess in the cylinder wall.
 13. An automatic valveaccording to claim 1 further comprising: an annular groove formed on thEouter periphery of the smaller diameter extension of the valve body; aseal ring positioned in the annular groove for cooperating with the wallof the cylinder upon movement of the valve body to the closed position,the outer dimension of the inner wall of the annular groove beingsmaller than the inner dimension of the seal ring and the dimension ofthe groove in the direction of flow being larger than the correspondingdimension of the seal ring, whereby the seal ring does not rest againstthe inner wall of the groove nor the downstream side of the groove whenthe seal ring is moved downstream within the cylinder.
 14. An automaticvalve according to claim 13, wherein the means for permitting controlledfluid escape from the cylinder includes means associated with theupstream side of the annular groove for permitting fluid flow past theinner side and upstream side of the seal ring to the region of thecylinder upstream of the seal ring.
 15. An automatic valve according toclaim 14, wherein the means associated with the upstream side of thegroove comprises a recess formed in the upstream groove side in flowcommunication with the region of the groove behind the seal ring and theregion of the cylinder upstream of the seal ring.
 16. An automatic valveaccording to claim 14, wherein the means associated with the groovemeans comprises a projection extending downstream from the upstreamgroove side so as to prevent at least a portion of the seal ring frommaking sealing engagement with the upstream side.
 17. An automatic valveaccording to claim 1, wherein the smaller diameter extension of thevalve body includes a section which cooperates with the cylinder innerwall for guiding the valve body.
 18. An automatic valve according toclaim 1, further comprising a quick-connection nipple carried by thehousing at the downstream end thereof.
 19. An automatic valve accordingto claim 1, wherein the housing is a substantially cylindrical body, thechamber comprises a central bore, the cylinder is dimensioned with anouter diameter less than the diameter of the chamber and is positionedconcentrically within the bore, and the second flow passage comprisesthe space between the cylinder and the chamber wall.